At the end of 2011, Novartis suspended the ALTITUDE Study, effectively ending the possibility that the direct renin inhibitor (DRI) Aliskiren will play a significant role in the management of patients with CKD already on an ACE or ARB. This development was disappointing but actually represents only part of a growing body of evidence that now casts major doubt on the use of microalbuminuria (MAU) as a treatment surrogate in patients with cardiovascular disease.
The use of MAU as a predictor of cardiovascular risk is sound and supported by a sizable evidence base. There is little doubt that patients with risks for cardiovascular disease who also have MAU are at far greater risk for adverse outcomes including death. In numerous studies, including the Heart Outcomes Prevention Evaluation (HOPE) Trial , MAU was the single most potent risk factor for adverse outcomes, with greater predictive power than diabetes, male gender, smoking and hypertension. The fascinating part of this observation is that even seemingly modest elevation in MAU was highly predictive of adverse events. It was very tempting then to anticipate a concomitant reduction in risk among patients whose MAU was targeted for therapeutic reduction with any of: (1) high dose ACE or ARB, (2) combination ACE and ARB, and most recently, (3) combination ACE or ARB with DRI. Unfortunately, recent prospective studies have essentially decimated this hypothesis and in all, proteinuria improved whereas patients did not or actually fared worse.